All wheel drive, walk behind mower

ABSTRACT

A drive system includes a first transmission, a second transmission and at least one flexible driving member. The first transmission is operably coupled to a first set of wheels to provide drive power to the first set of wheels responsive to engagement of the first transmission. The second transmission is operably coupled to a second set of wheels to provide drive power to the second set of wheels responsive to engagement of the second transmission. The at least one flexible driving member is operably coupled to a remote actuator and a drive shaft of the walk-behind outdoor power equipment device. The at least one flexible member selectively engages one of the first transmission or the second transmission to switch a walk-behind outdoor power equipment device between all wheel drive operation and another drive mode via the remote actuator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/468,355 filed Mar. 24, 2017, which is a continuation of U.S.application Ser. No. 14/377,736 filed on Aug. 8, 2014 (which issued onApr. 18, 2017 as U.S. Pat. No. 9,622,407), which is a national phaseentry of PCT/US2012/024853 filed Feb. 13, 2012, the entire contents ofeach of which are incorporated herein by reference.

TECHNICAL FIELD

Example embodiments generally relate to outdoor power equipment and,more particularly, relate to a walk behind lawn mower with selectableall wheel drive.

BACKGROUND

Yard maintenance tasks are commonly performed using various tools and/ormachines that are configured for the performance of correspondingspecific tasks. Certain tasks, like grass cutting, are typicallyperformed by lawn mowers. Lawn mowers themselves may have many differentconfigurations to support the needs and budgets of consumers.Walk-behind lawn mowers are typically relatively compact, havecomparatively small engines and are relatively inexpensive. Meanwhile,at the other end of the spectrum, riding lawn mowers, such as lawntractors, can be quite large. Riding lawn mowers can sometimes also beconfigured with various functional accessories (e.g., trailers, tillersand/or the like) in addition to grass cutting components. Riding lawnmowers can also be ruggedly built and have sufficient power, traction,and handling capabilities to enable operators to mow over rough terrain,if needed.

Walk behind models are often used when smaller lots or tighter areas areto be mowed. Some, relatively simple walk behind models may moveresponsive only to the pushing force provided by the operator. However,other models may provide power to the wheels to assist the operatorrelative to providing mobility for the lawn mower. In many instances,the lawn mower may have power provided to either the front set ofwheels, or the back set of wheels. The power may be provided, forexample, via a belt system that is selectively powered off the sameshaft that turns a blade for cutting grass.

More recently, some models have been provided with all wheel (or fourwheel) drive. These models may provide improved traction to assistoperators when mowing in rough terrain, on slopes, or in otherinhospitable areas. All wheel drive models are most commonly operated inall wheel drive on a full time basis. However, even though some modelshave been designed to enable operators to shift between all wheel driveand two wheel drive configurations, these models typically require atleast two actuators to be manipulated in order to initiate operation inall wheel drive mode or shift between two-wheel drive and all wheeldrive modes of operation.

BRIEF SUMMARY OF SOME EXAMPLES

Some example embodiments may therefore provide alternative methods foremployment of all wheel drive. In this regard, some embodiments mayprovide for a transfer between all wheel drive and another drive mode(e.g., two-wheel drive or no wheels being powered) using a singleactuator or actuation mechanism. In some embodiments, actuation of allwheel drive may be accomplished in the context of the selectiveengagement of a single drive belt at one of a first transmission (whichmay be operably coupled to the rear or front wheels) or secondtransmission (which may be operably coupled to the other one of the rearor front wheel) via the single actuator. The selective engagement may beprovided by rotation of either one of the transmissions (e.g., viarocking of the first or second transmission) or via rotation of an idlerpulley. Either of these rotating/rocking components (e.g., the idlerpulley or the transmission) may be engaged selectively via the singleactuator or actuation mechanism. In some embodiments, a dual belt drivesystem may be employed instead of the single belt drive system. Therotation of either of the transmissions or an idler pulley may also beused to selectively engage one of the drive belts to switch betweentwo-wheel and all wheel drive. However, as an alternative, a changespeed gear may be employed to selectively engage all wheel drive.

In one example embodiment, a drive system is provided. The drive systemmay include a first transmission, a second transmission and at least oneflexible driving member. The first transmission is operably coupled to afirst set of wheels to provide drive power to the first set of wheelsresponsive to engagement of the first transmission. The secondtransmission is operably coupled to a second set of wheels to providedrive power to the second set of wheels responsive to engagement of thesecond transmission. The at least one flexible driving member isoperably coupled to a remote actuator and a drive shaft of thewalk-behind outdoor power equipment device. The at least one flexiblemember selectively engages one of the first transmission or the secondtransmission to switch the walk-behind outdoor power equipment devicebetween two-wheel drive operation and all wheel drive operation via theremote actuator.

In another example embodiment, a lawn mower is provided. The lawn mowermay include a blade housing, an engine supported at least in part by theblade housing to selectively rotate a drive shaft, a mobility assemblyand a drive system. The mobility assembly may include a first set ofwheels and second set of wheels selectively operably coupled to theengine to provide mobility of the lawn mower responsive at least in partto operation of the engine. The drive system may include a firsttransmission, a second transmission and at least one flexible drivingmember. The first transmission may be operably coupled to the first setof wheels to provide drive power to the first set of wheels responsiveto engagement of the first transmission. The second transmission may beoperably coupled to the second set of wheels to provide drive power tothe second set of wheels responsive to engagement of the secondtransmission. The at least one flexible driving member may be operablycoupled to a remote actuator and the drive shaft. The at least oneflexible member may selectively engage one of the first transmission orthe second transmission to switch the lawn mower between two-wheel driveoperation and all wheel drive operation via the remote actuator.

Some example embodiments may provide an operator with a relatively easyway to switch between two-wheel and four wheel or all wheel drive withonly the use of a single actuator or actuation mechanism.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 illustrates a perspective view of a walk-behind lawn moweraccording to an example embodiment;

FIG. 2 illustrates a view of portions of a drive system of the lawnmower from below the blade housing of an example embodiment;

FIG. 3 illustrates a cutaway side view of a rear transmission of thedrive system according to an example embodiment;

FIG. 4 illustrates a cutaway side view of a first transmission of thedrive system according to an example embodiment;

FIG. 5 illustrates an example in which one of the primary idler pulleysis adjustable according to an example embodiment;

FIG. 6 illustrates a partially cutaway top view of the area surroundingthe second transmission to show another alternative embodiment in whichbelt tensioning relative to one of the drive pulleys may be provided bymovement of an idler pulley according to an example embodiment;

FIG. 7 illustrates a view of a two belt drive system from below theblade housing according to an example embodiment;

FIG. 8 illustrates a perspective view of components of the drive systemin isolation according to an example embodiment;

FIG. 9 shows a side view of a change-speed gear of an exampleembodiment;

FIG. 10 illustrates a cross sectional view along a rotational axis ofthe change-speed gear of FIG. 9 according to an example embodiment;

FIG. 11 shows the change speed gear in two-wheel drive operation modeaccording to an example embodiment; and

FIG. 12 show the change speed gear in four-wheel drive operation modeaccording to an example embodiment.

DETAILED DESCRIPTION

Some example embodiments now will be described more fully hereinafterwith reference to the accompanying drawings, in which some, but not allexample embodiments are shown. Indeed, the examples described andpictured herein should not be construed as being limiting as to thescope, applicability or configuration of the present disclosure. Rather,these example embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals refer tolike elements throughout. Furthermore, as used herein, the term “or” isto be interpreted as a logical operator that results in true wheneverone or more of its operands are true. As used herein, operable couplingshould be understood to relate to direct or indirect connection that, ineither case, enables functional interconnection of components that areoperably coupled to each other.

Some example embodiments described herein provide alternative methodsand/or structures for selective employment of all wheel drive on awalk-behind lawn mower. In this regard, some embodiments may provide fora transfer between all wheel drive and another drive mode (e.g., twowheel drive or no wheel drive) using a single actuator or actuationmechanism. Thus, for example, the lawn mower may be converted betweentwo-wheel and all wheel drive operation, or converted between no wheeldrive (e.g., where no drive power is coupled from the engine to eitherof the front or back wheels) and all wheel drive operation, by remoteaction of an operator without needing tools or complicatedmodifications. Some embodiments may employ a single drive belt, whileother embodiments may employ two drive belts.

FIG. 1 illustrates a perspective view of a walk-behind lawn mower 10 ofan example embodiment. The lawn mower 10 of FIG. 1 includes a bladehousing 20 that may house a rotatable cutting blade (not shown). Thecutting blade may be suspended above the ground at the end of arotatable shaft (e.g., a drive shaft—again not shown in FIG. 1) that maybe turned responsive to operation of an engine 30, such as a gasolinepowered engine. Operation of the engine 30 may be initiated by a recoilstarter via pulling of a recoil starter handle 32 by the operator.However, in other embodiments, the engine 30 may alternatively bestarted via a key, switch or other similar device.

The lawn mower 10 may include a mobility assembly on which a substantialportion of the weight of the lawn mower 10 may rest, when the lawn mower10 is stationary. The mobility assembly may also provide for movement ofthe lawn mower 10. In some cases, the mobility assembly may be drivenvia power from the engine 30 that may be selectively provided to eitheror both of front wheels 40 and back wheels 42, which make up themobility assembly. However, in some cases, the mobility assembly maysimply provide for mobility of the lawn mower 10 responsive to pushingby the operator if, for example, drive power is not being provided toboth the front wheels 40 and the back wheels 42. In other words, forexample, the mobility assembly may be an active or passive provider ofmobility for the lawn mower 10.

In some examples, the front wheels 40 and/or the back wheels 42 may beadjustable in their respective heights. Adjusting the height of thefront wheels 40 and/or the back wheels 42 may be employed in order toprovide a level cut and/or to adjust the height of the cutting blade. Insome embodiments, a local wheel height adjuster 44 may be provided atthe front wheels 40 and/or the back wheels 42. However, in otherembodiments, remote wheel height adjustment may also or alternatively bepossible.

Rotation of the cutting blade may generate grass clippings, and/or otherdebris that may be ejected from the blade housing 20. In some cases, theclippings/debris may be ejected from a side or rear of the blade housing20. When rear discharge is employed, many such lawn mowers may employ abagging attachment 50 to collect discharged clippings/debris. However,bagging attachments may also be used for side discharge models in somecases. The bagging attachment 50 may be removable to enable the operatorto empty the bagging attachment 50.

In an example embodiment, the lawn mower 10 may further include a handleassembly. The handle assembly of FIG. 1 may include two handle members60 that extend generally rearward and upward from opposing sides of arear portion of the blade housing 20. The handle members 60 may besubstantially parallel to each other and may be connected to each otherat their distal ends via a cross bar 62. The handle members 60 may beadjustable in length or may be foldable to reduce the amount of spacethat the lawn mower 10 consumes when stored or shipped.

In some embodiments, various controls may be provided proximate to thecross bar 62 and/or one or more of the handle members 60. For example,the pictured embodiment shows a trigger controller 70 and a presence bar72. When the presence bar 72 is held proximate to the cross bar 62,power may be enabled to be delivered to either or both of the frontwheels 40 and the back wheels 42. The trigger controller 70 may be usedto provide for remote actuation of various control functions. Forexample, pulling either or both of the movable members of the triggercontroller 70 may cause adjustments to be made to one or moretransmissions of the lawn mower 10 or may cause movement of componentsto actuate shifting from no drive operation (e.g., zero-wheel drivewhere movement is only responsive to operator pushing) to an all wheeldrive configuration as described in greater detail below. As such, thetrigger controller 70 provides one example of a remote actuator, oractuation mechanism, that may be employed to practice an exampleembodiment. In some cases, however, the trigger controller 70 may bereplaced by a lever, knob, or other actuation device that may beoperably coupled to a speed change gear, one or more transmissions orlinkages associated therewith, and/or one or more idler pulleys orlinkages associated therewith.

In an example embodiment, the remote actuator (e.g., the triggercontroller 70) may be configured to provide a single actuator enabled toshift the lawn mower 10 between all wheel drive operation and anotherdrive mode (e.g., in either direction). Some example embodiments mayaccomplish the above-described functionality with a single drive belt,while other example embodiments may employ two drive belts. FIGS. 2-6illustrate an example employing a single drive belt and FIGS. 7-8illustrate an example employing two drive belts.

FIG. 2 illustrates a view from below the blade housing 20 of an exampleembodiment. In other words, FIG. 2 is a view from below ground levellooking up into the under side of the blade housing 20. As shown in FIG.2, a single drive belt 100 may be routed to a first transmission 110,which may operably coupled via axle 112 to selectively provide power toturn the front wheels 40 when the first transmission 110 is engaged, anda second transmission 120, which may be operably coupled via axle 122 toselectively provide power to turn the rear wheels 42 when the secondtransmission 120 is engaged. The first transmission 110 may include afirst drive pulley 114 that is capable of engaging the drive belt 100when there is sufficient tension (or lack of slack) between the drivebelt 100 and the first drive pulley 114. The second transmission 120 mayinclude a second drive pulley 124 that is capable of engaging the drivebelt 100 when there is sufficient tension (or lack of slack) between thedrive belt 100 and the second drive pulley 124. In an exampleembodiment, the amount of tension (or slack) between the drive pulleysand the drive belt 100 may be adjusted remotely for at least one of thedrive pulleys as is shown and described in FIGS. 3-6.

The drive belt 100 may be operably (directly or indirectly) coupled to adrive shaft 130 that turns a blade (not shown) for cutting grass. Forexample, the drive shaft 130 may rotate responsive to operation of theengine 30 and turn a drive shaft pulley 132 that may be operably coupledto the drive shaft 130. The rotation of the drive shaft pulley 132 maycause corresponding movement of the drive belt 100 via engagementbetween the drive shaft pulley 132 and the drive belt 100 based ontension maintained between the drive shaft pulley 132 and the drive belt100. The movement of the drive belt 100 may thereafter be selectivelytransferred to the first transmission 110 and/or the second transmission120 via respective ones of the first drive pulley 114 and the seconddrive pulley 124.

In an example embodiment, one or more idler pulleys (e.g., primary idlerpulleys 140 and 142 and secondary idler pulley 144) may be disposedproximate to the drive shaft pulley 132 in order to assist in providingtension between the drive belt 100 and the drive shaft pulley 132 and toprovide for a desired alignment of the drive belt 100 as it engages thedrive shaft pulley 132. Although three idler pulleys are shown in FIG.2, it should be appreciated that either more or fewer idler pulleys maybe employed in alternative embodiments. Furthermore, the location of theidler pulleys need not necessarily be the same as that which is shown inFIG. 2.

In the example of FIG. 2, the primary idler pulleys 140 and 142 aredisposed substantially on opposite sides of the drive shaft pulley 132and engage an opposite surface of the drive belt 100 than the surfaceengaged by the drive shaft pulley 132. In this regard, for example, thedrive shaft pulley 132 engages an interior surface of the drive belt100, while the primary idler pulleys 140 and 142 engage an exteriorsurface of the drive belt 100 to provide tension or tend to pull thedrive belt 100 into contact with the drive shaft pulley 132. Meanwhile,the secondary idler pulley 144 is disposed to engage a portion of thedrive belt 100 that extends between the first transmission 110 and thesecond transmission 120. The secondary idler pulley 144 also engages anexterior surface of the drive belt 100 in order to tend to pull thedrive belt 100 into engagement with the other components of the drivesystem (e.g., the drive shaft pulley 132, the first drive pulley 114 andthe second drive pulley 124). Given the configuration shown in FIG. 2,movement of the secondary idler pulley 144 closer toward the drive shaftpulley 132 would tend to tighten the drive belt 100. Meanwhile, movementof either or both of the primary idler pulleys 140 and 142 toward thesecondary idler pulley 144 would also tend to tighten the drive belt100. In some embodiments, a position of one or more of the idler pulleysmay be adjustable in order to adjust the tightness of the drive belt100.

When the drive belt 100 has sufficient tension with respect to itsengagement with the first drive pulley 114 and the second drive pulley124, both the first transmission 110 and the second transmission 120 maybe engaged and all wheel drive operation may be provided. However, ifthe drive belt 100 does not have sufficient tension with respect to itsengagement with one of either the first drive pulley 114 or the seconddrive pulley 124, the corresponding slack created thereby may translateinto a situation in which sufficient tension may not be provided betweenthe drive belt 100 and the drive shaft pulley 132 to turn the driveshaft pulley 132. Consequently, no drive operation may be achieved. Inthis regard, if the drive shaft pulley 132 is not turned, then both thefirst drive pulley 114 and the second drive pulley 124 lack sufficienttension, and drive power may not be communicated to the front wheels 40and the rear wheels 42.

By providing a mechanism for altering belt tensioning of the drive belt100 relative to the first transmission 110 and/or the secondtransmission 120, the operator of the lawn mower 10 may controltransitions between all wheel drive operation and another drive mode(namely no drive operation). The alteration of belt tensioning may beaccomplished via a number of different ways. Example embodiments of thepresent invention may enable the use of a single remote actuator toprovide for belt tensioning control and thereby further provide foroperator control of transitions between all wheel drive operation andanother drive mode. At least in relation to the single drive beltembodiment shown in FIG. 2, belt tensioning may be controlled at leastby enabling movement of an idler pulley to adjust tension of the drivebelt 100 relative to at least one of the drive pulleys, or by enablingan adjustment of tension via movement of the drive pulley itself.

FIGS. 3 and 4 illustrate example embodiments showing a belt tensioningscheme via which belt tension is adjusted by moving a position of thedrive pulley itself. In this regard, FIGS. 3 and 4 show rockingtransmissions that may be rocked (or rotated) at least to some degree toadjust belt tension of the drive belt 100 and thereby enable switchingbetween all wheel drive operation and another drive mode.

FIG. 3 illustrates a cutaway side view of the second transmission 120(e.g., a rear transmission) according to an example embodiment. As shownin FIG. 3, the drive belt 100 may engage the second drive pulley 124,which may be operably coupled to the second transmission 120. In thisexample, the second drive pulley 124 is mounted to a top portion of thesecond transmission 120, but other arrangements could alternatively beprovided. The second transmission 120 may be enabled to be rocked orslightly rotated as shown by arrow 200 in order to adjust belt tension.For example, when the second transmission 120 is elevated (or notrocked/rotated), the tension between the drive belt 100 and the seconddrive pulley 124 may not be sufficient and slack may be provided in thedrive belt 100. Accordingly, there may not be sufficient tension for thedrive shaft pulley 132 to turn the drive belt 100 to force the seconddrive pulley 124. However, rotation or rocking of the secondtransmission 120 (as shown by arrow 200) may cause the second drivepulley 124 to be slightly farther away from the drive shaft pulley 132(as shown by arrow 202) and increase the tension between the drive belt100 and the second drive pulley 124 to a point where tension isincreased between the drive shaft pulley 132 and the drive belt 100causing corresponding movement of the second drive pulley 124 to providedrive power to the rear wheels 42 via the second transmission 120 andmovement of the first drive pulley 114 to provide drive power to thefront wheels 40 via the first transmission 110. In an alternativearrangement, the second transmission 120 may be rocked or rotated inorder to decrease the tension, rather than increase the tension, betweenthe drive belt 100 and the second drive pulley 124.

In some embodiments, instead of (or in addition to) providing the reartransmission as a rotating or rocking transmission as shown in FIG. 3,the front transmission (e.g., the first transmission 110) may beprovided as a rotating or rocking transmission as shown in FIG. 4, whichshows a cutaway side view of the first transmission 110 according to anexample embodiment. As shown in FIG. 4, the first transmission 110 maybe rotate or rock as shown by arrow 210. In this example, rotation orrocking of the first transmission 110 may cause the first transmission110 to move slightly away from the drive shaft 130 as shown by arrow212. This movement may increase the tension between the drive belt 100and the first drive pulley 114 in a similar manner to that which isdescribed above in connection with the description of FIG. 3.

In an example embodiment, a single actuator (e.g., the triggercontroller 70 or some other remote actuation mechanism, lever, knob,etc.) may be operated in order to cause the first transmission 110 (orthe second transmission 120) to rock or rotate as shown in FIG. 4 (orFIG. 3). In cases where only one of the transmissions is adjustable,zero-wheel drive or no drive power operation may be the default mode ofoperation. However, all wheel drive operation may be initiatedresponsive to rocking or rotation of the adjustable transmission via thesingle actuator. Accordingly, a single actuator may be used totransition between no drive power operation and all wheel driveoperation.

As an alternative to causing belt tension adjustment via adjustment(e.g., rocking or rotation) of the transmission or transmissions, one ormore movable idler pulleys may be provided to adjust belt tension. FIG.5 illustrates an example in which one of the primary idler pulleys(e.g., idler pulley 140′) is adjustable. Adjustable idler pulley 140′may be adjustable responsive to operation of the single actuator (e.g.,the trigger controller 70 or some other remote actuation mechanism,lever, knob, etc.) in order to move the adjustable idler pulley 140′closer to the secondary idler pulley 144 (or simply in a direction thattends to tighten the drive belt 100) as shown by arrow 220. Movement ofthe adjustable idler pulley 140′ may cause tension between the drivebelt 100 and the second drive pulley 124 to be increased to a levelsufficient to cause the second drive pulley 124 to rotate responsive tomovement of the drive belt 100 due to a lack of slack between the drivebelt 100 and the drive shaft pulley 132. Prior to movement of theadjustable idler pulley 140′ in the direction shown by arrow 220, thebelt tension provided between the drive belt and the second drive pulley124 may not be sufficient to cause slack to be taken up in the drivebelt 100 and thus the drive belt 100 is not turned by the drive shaftpulley 132. Thus, in this embodiment also, a single actuator may beemployed to remotely enable a shift between all wheel drive operationand no drive power operation. It should be appreciated thatalternatively (or additionally), primary pulley 142 may be adjustable ina similar fashion to allow tensioning of the drive belt 100 relative tothe first drive pulley 114.

FIG. 6 illustrates a partially cutaway top view of the area surroundingthe second transmission 120 to show another alternative embodiment inwhich belt tensioning relative to one of the drive pulleys may beprovided by movement of an idler pulley. However, in the example of FIG.6, a movable idler pulley 230 is provided proximate to the second drivepulley 124 and the primary idler pulley 140 may be stationary. In thisexample, the movable idler pulley 230 may be disposed proximate to thedrive belt 100 at a portion of a rotatable arm 240. The rotatable arm240 may be rotated as shown by arrow 250 responsive to operation of thesingle actuator (e.g., the trigger controller 70 or some other remoteactuation mechanism, lever, knob, etc.). When the rotatable arm 240rotates as shown by arrow 250, the movable idler pulley 230 may contactan exterior surface of the drive belt 100 to reduce the slack of thedrive belt 100 and increase the tension between the drive belt 100 andthe second drive pulley 124. The tension may be increased to a levelsufficient to cause movement of the drive belt 100 to turn the seconddrive pulley 124 via the rotation of the drive shaft pulley 132.

Although FIG. 6 shows the movable idler pulley 230 being employed inconnection with the second transmission 120, it should be appreciatedthat a movable idler pulley may also or alternatively be employed inconnection with the first transmission 110. Thus, either or both of thefirst transmission 110 and the second transmission 120 may beselectively engaged to be driven via movement of the drive belt 110 viaa movable idler pulley disposed proximate to the first transmission 110or the second transmission 120, respectively, to adjust tension betweenthe drive belt 110 and the first drive pulley 114 or the second drivepulley 124 using a single actuator.

As indicated above, selective switching between all wheel driveoperation and no drive power operation via operation of a singleactuator may be accomplished with a single drive belt. However, somealternatives may be provided in connection with a dual drive beltembodiment. FIGS. 7 and 8 illustrate an example embodiment in which atwo belt drive system are employed. In this regard, FIG. 7 illustrates aview of the two belt drive system from below the blade housing 20 andFIG. 8 illustrates a perspective view of components of the drive systemin isolation. Similar to the embodiments described above, the lawn mower10 may include the first transmission 110 drivable by the first drivepulley 114 and capable of turning the first axle 112 along with thesecond transmission 120 drivable by the second drive pulley 124 andcapable of turning the second axle 122. However, the first and seconddrive pulleys 114 and 124 may each engage different drive belts.Moreover, the drive shaft pulley 132′ may be configured to accommodate,and have the potential to turn, two separate drive belts including afirst drive belt 300 and a second drive belt 310. In an exampleembodiment, the drive shaft pulley 132′ may be configured to have astacked arrangement of pulleys operably coupled to the drive shaft 130to turn respective ones of the first and second drive belts 300 and 310.

In an example embodiment, one of the first drive belt 300 or the seconddrive belt 310 may be configured to be tensioned sufficiently to turnits respective first or second drive pulley 114 or 124 by default.Tension may be selectively increased or decreased for the other one ofthe first drive belt 300 or second drive belt 310 to switch betweentwo-wheel drive operation and all wheel drive operation via the singleactuator. The particular one of the first drive pulley 114 or the seconddrive pulley 124 that is configured to be tensioned to turn responsiveto movement of its corresponding drive belt by default may be alternatedin corresponding alternative embodiments. Moreover, any of thetensioning mechanisms described above in connection with thedescriptions of FIGS. 3-6 may be employed. Thus, for example, either thefirst transmission 110 or the second transmission 120 may be enabled tobe rocked or rotated (e.g., responsive to actuation of the singleactuator) to adjust belt tension similar to the examples shown in FIGS.3 and 4. Alternatively, one or more idler pulleys may be used to adjusttension of one of the drive belts and the idler pulleys may be disposedproximate to the drive shaft pulley 132′ or proximate to the first drivepulley 114 or second drive pulley 124 similar to the examples shown inFIGS. 5 and 6.

However, one possible alternative to providing rocking or rotation ofone or more of the transmissions, or providing movement of one or moreidler pulleys to cause tensioning adjustments for one of the drivebelts, may be to configure the drive shaft pulley 132′ as a dual pulleythat is enabled to selectively engage at least one of the belts engagedwith the dual pulleys. The selectively engageable dual pulley of oneexample embodiment may be referred to as a change-speed gear. FIGS. 9-12illustrate various examples of a change-speed gear to facilitatedescription of some example embodiments.

FIG. 9 shows a side view of a change-speed gear 400 of an exampleembodiment and FIG. 10 illustrates a cross sectional view along arotational axis of the change-speed gear 400 of FIG. 9. As shown inFIGS. 9 and 10, the change-speed gear 400 may include a first fixed disc410 and a second fixed disc 420, each of which may be disposed atopposite ends of the change-speed gear 400 facing one another. Thechange-speed gear 400 may also include a sliding disc 430 disposedbetween the first and second fixed discs 410 and 420. The sliding disc430 may be biased toward the first fixed disc 410 in order to supplysufficient force to engage a first drive belt 440 that is disposedbetween the first fixed disc 410 and the sliding disc 430. In an exampleembodiment, a spring 450 (e.g., a wave spring or any other suitable typeof spring) may be used to provide the biasing force. Accordingly, untilthe biasing force of the spring 450 is overcome, the sliding disc 430may not be positioned to provide friction with sufficient force toengage a second drive belt 460 that is disposed between the second fixeddisc 420 and the sliding disc 430.

In an example embodiment, the first drive belt 440 may be engagedregardless of the position of the sliding disc 430 when the device is indrive mode. Thus, at least two-wheel drive operation may always beprovided via the first drive belt 440 when in drive mode. However, insome embodiments, the tension between the first drive belt 440 and thesliding disc 430 may also be adjustable via the single actuator in orderto permit transitioning to no drive operation. When in two-wheel driveoperation, the second drive belt 460 may also be engaged to cause ashift from two-wheel drive operation to all wheel drive operation byovercoming the spring 450. In an example embodiment, a remote actuatormay be used to overcome the spring force of the spring 450. The remoteactuator may be operated from the handle assembly of the device (e.g.,the trigger controller 70) or a knob, lever or other actuator disposedproximate to a housing of the device. In some embodiments, drive paddlesor another method of exerting a force may be employed to overcome thebiasing force of the spring 450. For example, drive paddles may bepushed in to about ⅔ of their full stroke for two-wheel drive operationand, responsive to operation of the remote actuator, the paddles may beenabled to use the final ⅓ of the full stroke and thereby overcome thespring 450 to engage four-wheel drive operation.

FIGS. 11 and 12 show the change speed gear 400 in two-wheel drive andfour-wheel drive operation, respectively. As shown in FIG. 11, thesliding disc 430 is pushed upward by the spring 450 to keep any drivebelt disposed between the sliding disc 430 and the second fixed disc 420from rotating. However, as shown in FIG. 12, when the spring 450 forceis overcome, the sliding disc 430 moves downward and the drive beltdisposed between the sliding disc 430 and the second fixed disc 420would be engaged for rotation.

Thus, according to various example embodiments, actuation of all wheeldrive may be accomplished in the context of the selective engagement ofa single drive belt at one of a first transmission (which may beoperably coupled to the rear or front wheels) or second transmission(which may be operably coupled to the other one of the rear or frontwheel) via the single actuator. The selective engagement may be providedby rotation of either one of the transmissions (e.g., via rocking of thefirst or second transmission) or via rotation of an idler pulley. Eitherof these rotating/rocking components (e.g., the idler pulley or thetransmission) may be engaged selectively via the single actuator oractuation mechanism. However, in some embodiments, a dual belt drivesystem may be employed instead of the single belt drive system. Therotation of either of the transmissions or an idler pulley may also beused to selectively engage one of the drive belts to switch betweentwo-wheel and all wheel drive. However, as an alternative, a changespeed gear may be employed to selectively engage all wheel drive.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Moreover, although the foregoing descriptions and the associateddrawings describe exemplary embodiments in the context of certainexemplary combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative embodiments without departing from the scopeof the appended claims. In this regard, for example, differentcombinations of elements and/or functions than those explicitlydescribed above are also contemplated as may be set forth in some of theappended claims. In cases where advantages, benefits or solutions toproblems are described herein, it should be appreciated that suchadvantages, benefits and/or solutions may be applicable to some exampleembodiments, but not necessarily all example embodiments. Thus, anyadvantages, benefits or solutions described herein should not be thoughtof as being critical, required or essential to all embodiments or tothat which is claimed herein. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

That which is claimed:
 1. A lawn mower comprising: a blade housing; an engine supported at least in part by the blade housing and configured to rotate a drive shaft; a mobility assembly operably coupled to the engine and configured to provide mobility of the lawn mower responsive at least in part to operation of the engine, wherein the mobility assembly comprises a first set of wheels and a second set of wheels; a drive system comprising: a first transmission operably coupled to the first set of wheels; a second transmission operably coupled to the second set of wheels; a single flexible driving member; and an idler pulley; and a remote actuator operably coupled to the drive system, wherein the idler pulley moves from a first position to a second position responsive to operation of the remote actuator, wherein the single flexible driving member enables switching the lawn mower from a no wheel drive operation to an all wheel drive operation based on movement of the idler pulley from the first position to the second position.
 2. The lawn mower of claim 1, wherein the drive system further comprises a second idler pulley, wherein, in the all wheel drive mode, the second idler pulley engages the flexible driving member, and wherein the idler pulley is closer to the second idler pulley in the second position than in the first position.
 3. The lawn mower of claim 1, wherein the drive system further comprises a second idler pulley, wherein, in the all wheel drive mode, the second idler pulley engages the flexible driving member, and wherein, responsive to operation of the remote actuator, the idler pulley moves towards the second idler pulley.
 4. The lawn mower of claim 3, wherein the drive system further comprises a third idler pulley, wherein the drive shaft comprises a drive shaft pulley, wherein the idler pulley and the third idler pulley are disposed substantially on opposite sides of the drive shaft pulley relative to each other, and wherein, in the all wheel drive mode, the idler pulley and the third idler pulley engage the second surface of the flexible driving member.
 5. The lawn mower of claim 1, wherein the first transmission comprises a first drive pulley, wherein the drive shaft comprises a drive shaft pulley, wherein, in the all wheel drive mode, the first drive pulley engages the flexible driving member, and wherein, in the all wheel drive mode, the idler pulley is positioned substantially between the drive shaft pulley and the first drive pulley, and is positioned closer to the drive shaft pulley than to the first drive pulley.
 6. The lawn mower of claim 1, wherein the first transmission comprises a first drive pulley, wherein the drive shaft comprises a drive shaft pulley, wherein, in the all wheel drive mode, the first drive pulley engages the flexible driving member, wherein the idler pulley is disposed closer to the first drive pulley than to the drive shaft pulley, and wherein, responsive to operation of the remote actuator, the idler pulley moves relative to the first drive pulley.
 7. The lawn mower of claim 6, wherein the idler pulley is disposed at a portion of a rotatable arm, and wherein, responsive to operation of the remote actuator, the rotatable arm rotates to cause the idler pulley to move to engage the flexible driving member with the first drive pulley.
 8. The lawn mower of claim 7, wherein the first transmission is a rear transmission positioned substantially between the drive shaft and a handle assembly of the lawn mower.
 9. The lawn mower of claim 1, wherein the flexible driving member is a drive belt.
 10. The lawn mower of claim 1, wherein the remote actuator comprises a lever.
 11. The lawn mower of claim 1, wherein, responsive to operation of the remote actuator, the first transmission is configured to drive the first set of wheels through a range of increasing speeds while the lawn mower is switched from the no wheel drive mode to the all wheel drive mode.
 12. The lawn mower of claim 1, wherein the idler pulley is disposed proximate a drive pulley disposed at the first transmission.
 13. The lawn mower of claim 1, wherein the idler pulley is disposed proximate to the drive shaft.
 14. A drive system comprising: a first transmission operably coupled to a first set of wheels of a walk-behind outdoor power equipment device; a second transmission operably coupled to a second set of wheels of the walk-behind outdoor power equipment device; a single flexible driving member; and an idler pulley, wherein the idler pulley moves from a first position to a second position responsive to operation of a remote actuator of the walk-behind outdoor power equipment device, wherein the single flexible driving member enables switching the lawn mower from a no wheel drive operation to an all wheel drive operation based on movement of the idler pulley from the first position to the second position.
 15. The drive system of claim 14, wherein the drive system further comprises a second idler pulley, wherein, in the all wheel drive mode, the second idler pulley engages the flexible driving member, and wherein the idler pulley is closer to the second idler pulley in the second position than in the first position.
 16. The drive system of claim 14, wherein the drive system further comprises a second idler pulley, wherein, in the all wheel drive mode, the second idler pulley engages the flexible driving member, and wherein, responsive to operation of the remote actuator, the idler pulley moves towards the second idler pulley.
 17. The drive system of claim 16, wherein the drive system further comprises a third idler pulley, wherein the drive shaft comprises a drive shaft pulley, wherein the idler pulley and the third idler pulley are disposed substantially on opposite sides of the drive shaft pulley relative to each other, and wherein, in the all wheel drive mode, the idler pulley and the third idler pulley engage the second surface of the flexible driving member.
 18. The drive system of claim 14, wherein the first transmission comprises a first drive pulley, wherein the drive shaft comprises a drive shaft pulley, wherein, in the all wheel drive mode, the first drive pulley engages the flexible driving member, and wherein, in the all wheel drive mode, the idler pulley is positioned substantially between the drive shaft pulley and the first drive pulley, and is positioned closer to the drive shaft pulley than to the first drive pulley.
 19. The drive system of claim 14, wherein the first transmission comprises a first drive pulley, wherein the drive shaft comprises a drive shaft pulley, wherein, in the all wheel drive mode, the first drive pulley engages the flexible driving member, wherein the idler pulley is disposed closer to the first drive pulley than to the drive shaft pulley, and wherein, responsive to operation of the remote actuator, the idler pulley moves relative to the first drive pulley.
 20. The drive system of claim 19, wherein the idler pulley is disposed at a portion of a rotatable arm, and wherein, responsive to operation of the remote actuator, the rotatable arm rotates to cause the idler pulley to move to engage the flexible driving member with the first drive pulley. 